Psion Inc.

Steven William Maddigan

Dimitri Gabriel Epassa Habib

A method and system are set forth for enabling software control of a power management unit (PMU) in a System-On-a-Chip (SoC) device to effect changes in power state without having to adjust external board level states. In one embodiment, once the SoC system controller has been booted, it communicates with the PMU over a communication bus and is able to request changes in power states without requiring external trigger events. Complete remote control of power states according to the method and system set forth herein provides flexibility when debugging and testing SoC devices because there is no need to alter external board states. Also, providing programmable changes in reset states as an alternative to full system reset preserves state data so that the system can be restarted efficiently and quickly from known conditions.

Method and system for controlling reset state change in a system-on-a-chip device

A flexible and scalable bi-directional CDC interface is set forth between clock domains in a SoC device. The interface comprises a pulse sync circuit for receiving a pulse synchronized to the source clock domain and in response outputting a busy signal to the source clock domain and outputting the pulse synchronized to said destination clock domain; an input register for latching data from said source clock domain in response to a transition of said source clock in the event said busy signal is not active and preventing said data from being latched in the event said busy signal is active so as not to corrupt previously latched data; and an output register for receiving said pulse from said pulse sync circuit and in response latching said pulse from said input register on a transition of said destination clock.

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Mississauga, Canada

Steven William Maddigan